Sodium‐dependent isoleucine transport in the methanogenic archaebacterium Methanococcus voltae

Abstract
Methanococcus voltae possesses a Na+‐dependent transport system for isoleucine which requires for optimum rates a CO2/H2 atmosphere. The K m for the system is 4.5 μM with a V max of 1.5 nmol·min−1·mg dry wt−1. Approximately 75% of the label can be released from the cell pool following short‐term experiments with gradients of isoleucine reaching 100 (in/out). Transport is inhibited by ionophores and N‐ethyl maleimide. Only valine and leucine effectively compete with isoleucine for transport.